BARTINGTON INSTRUMENTS
Page 9 of 20 OM0382/9
See Figures 4 and 5 for circuitry diagrams. See
Introduction to the Probes
for the principles of
fluxgate operation.
The alternating field used in the operation of the probes is driven by a high purity alternating
signal (the excitation signal) from the probe excitation oscillator to the excitation winding.
The axial component (i.e. the component aligned with the axis) of any magnetic field intercepted
by the probe produces a signal which is filtered to eliminate unwanted noise from the excitation
signal. Following detection, any error arising from the processing is fed back to the probe via a
current converter and the feedback winding, where nulling of the magnetic field occurs.
In this way, with the error removed, a precise measurement of field strength is obtained in the
form of a voltage which is fed to the auto-ranging 4½ digit display and analogue output socket.
The battery charger, rechargeable battery and voltage regulators power the electronics unit.
4.2.1. Additional Circuitry for Mag-01H
The Mag-01H contains an attenuator which, when selected by the x10 range control switch,
reduces the current feedback to the probe and thereby increases the sensitivity by a factor of 10.
The Mag-01H also contains a switched precision offset current control which can be used to
back-off field strength values and thereby display or record measurements to the highest
resolution.
